At the end of the feedback survey I send to the participants of the workshops I ask for 4 words that sum up the experience. I started to do this in workshops with kids ( but with 3 words ) because it as a good way to get them to reflect on their experience, talk about what they had done and get feedback yourself at the same time. So for adults I extended it to 4 words and it gives you lots of scope for understanding the outcomes of the interventions.